In a known image processing method, in an image acquired by using a photographing device, such as a digital camera, the square root of the variance of the signal levels of a pixel of interest and eight peripheral pixels therearound, i.e., the standard deviation of these pixels, is calculated, a degree of prominence indicating how prominent the signal level of the pixel of interest is compared with the signal levels of the peripheral pixels is calculated, and the pixel of interest is determined to be a white defect in the case where the degree of prominence is greater than a predetermined upper limit, whereas the pixel of interest is determined to be a black defect in the case where the degree of prominence is less than a predetermined lower limit (e.g., see Patent Literature 1).